The Severity Index Project has developed an initial methodology for constructing severity indexes for EMS evaluation. The method has been successfully applied to acute ischemic heart disease (IHD). But IHD appears to be a relatively simple application--mathematically speaking. In the work proposed for the second year, we will address the developmental methodology to indexing severity of multiple trauma, a mathematically more complex topic because of interacting, functionally unrelated concomitant injury processes each contributing to severity. In the indicator elicitation process (comprising small groups of physicians interacting in manner controlled by a process facilitator) particular attention will be given to tailoring elicitation to the data needs of models necessary to represent interacting systems of severity indicators. Several indexes will be developed using alternative approaches to the scaling problem. These will be cross-validated against implicit-review judgments of severity independently made by panels of physicians uninvolved in index development. Indexes will also be preliminarily applied to interfacility evaluation comparison in judging acceptability of care and its relationship to patient outcome data. The products of the work should be a validated severity index for multiple trauma and a methodology useable by EMS reseachers to index severity for any EMS condition.